Liquefaction Risk Assessment in Arlington, TX

Walking a site in Arlington after a heavy rain, you notice the silty sand getting soft underfoot. That's the first clue a deeper problem might exist—liquefaction potential when the ground shakes. The USGS hazard maps put this part of the Dallas–Fort Worth metroplex in a moderate seismic zone, and with the Eastern Margin of the Fort Worth Basin's alluvial deposits, loose saturated sands can lose strength fast. We run field testing and lab programs that quantify that risk, not guess at it. If you're developing off Pioneer Parkway or near the Trinity River floodplain, it pays to know what's under the asphalt before you pour a foundation. Our approach ties directly to the SPT drilling data that NCEER methods require for cyclic stress ratio calculations.

Liquefaction failure isn't just about ground shaking—it's about what happens in the seconds after, when the soil turns to slurry and foundations lose bearing.

Methodology and scope

Arlington sits on the Barnett Shale, but the near-surface geology is dominated by Pleistocene-age terrace deposits and Holocene alluvium along the West Fork of the Trinity River. These formations can contain lenses of clean, poorly graded sand with groundwater at depths as shallow as 8 to 15 feet in wet years. That combination—loose granular soil plus high water table—is exactly the profile that triggers liquefaction concern under ASCE 7-22 Section 11.8.3. Our analysis starts by correlating SPT N-values with fines content to estimate the factor of safety against triggering, following the Youd and Idriss (2001) framework. We then quantify expected settlement and lateral spread displacement, because even a few inches of differential movement can shear utility connections and wreck slab-on-grade performance in commercial buildings along Interstate 20.

Local geotechnical context

The biggest misconception we see in North Texas is that liquefaction is only a West Coast problem. Arlington's seismic hazard is real, driven by the deep Meers Fault system in Oklahoma and the historic 1895 seismic event near Dallas. A magnitude 5.5 or greater event within 50 miles could trigger cyclic mobility in the sandy channel fills found beneath older industrial zones near Division Street. The risk compounds when loose fill was placed decades ago without compaction records—those layers are prime candidates for flow liquefaction. If the factor of safety drops below 1.1 for critical structures, we don't file a report and walk away; we work through ground improvement options like deep soil mixing or vibrocompaction to raise the resistance before the first structural column goes in.

Typical values

Parameter	Typical value
Methodology	NCEER/Youd-Idriss (2001) simplified procedure
Field test	SPT per ASTM D1586-18; CPTu per ASTM D5778
Lab index tests	ASTM D4318 (Atterberg), ASTM D422/D6913 (grain size)
Cyclic resistance ratio	CRR corrected for fines content (FC) and overburden
Seismic demand	Mapped Ss and S1 per ASCE 7-22, site class per Vs30
Output parameters	FS against triggering, LPI, post-liquefaction settlement
Applicable code	IBC 2024 Chapter 18, Arlington amendments

Complementary services

Liquefaction Screening & Factor of Safety

Using SPT or CPT data from your site, we compute the cyclic stress ratio and cyclic resistance ratio for each critical layer, delivering a factor of safety profile that satisfies the Arlington building official's plan review requirements.

Lateral Spread and Settlement Analysis

Where the factor of safety drops below 1.0, we estimate horizontal displacement using the Bartlett and Youd empirical model and calculate post-liquefaction volumetric strain to forecast total and differential settlement.

Ground Improvement Recommendations

When the site soils fail to meet performance criteria, we provide design parameters for stone columns, deep dynamic compaction, or permeation grouting to densify the liquefiable layer and bring the FS above the IBC threshold.

Relevant standards

ASCE 7-22 Minimum Design Loads and Associated Criteria for Buildings, IBC 2024 (International Building Code) Chapter 18, ASTM D1586-18 Standard Test Method for SPT and Split-Barrel Sampling of Soils, ASTM D5778-20 Standard Test Method for Electronic Friction Cone and Piezocone Penetration Testing of Soils, NCEER Workshop (Youd et al., 2001) Liquefaction Resistance of Soils

Quick answers

How much does a liquefaction analysis cost for a site in Arlington?

For a standard commercial lot requiring two SPT borings with lab index testing and a full liquefaction report, budgets typically run between US$2,360 and US$3,740. The spread depends on depth to refusal, number of samples tested for fines content, and whether CPT soundings are added to refine the stratigraphy. We provide a fixed-fee proposal after reviewing the geotechnical boring layout.

Is liquefaction a real concern in North Texas, or just a code formality?

It is a genuine geotechnical concern. The combination of Holocene alluvial sands along the Trinity River tributaries and a shallow groundwater table in wet years creates conditions where moderate shaking—from a local M5+ event—could trigger cyclic mobility. ASCE 7-22 Section 11.8 requires evaluation for site class E and F profiles, and Arlington plan reviewers enforce this for essential facilities.

What field data do you need to run the analysis?

We need SPT N-values corrected for energy, rod length, and overburden, along with the percent fines and plasticity index from split-spoon samples. If you have CPTu soundings, we can refine the layer boundaries using the soil behavior type index. For sites with no prior investigation, we mobilize our drilling crew to perform the borings and lab testing under one scope.

What happens if the site fails the liquefaction check?

Failing means the factor of safety against triggering is below the IBC minimum for the risk category. We don't stop there. The report includes ground improvement options—vibrocompaction, stone columns, or deep soil mixing—with design parameters to densify the critical layer. We can also recommend a deep foundation alternative with piles bearing below the liquefiable zone.